Method and apparatus for ACL reconstruction using retrograde cutter

ABSTRACT

A method and apparatus for anterior cruciate ligament (ACL) reconstruction using holes in bone created by retrograde cutting. A rotary cutter, mounted onto an insertion post of a tibial guide, is inserted through an anteromedial portal and the rotary cutter placed on the anatomical origin of an ACL tibial insertion. A drill pin is drilled through the tibia and advanced until it contacts and engages a cannulation in the rotary cutter on the guide. Further rotation of the drill pin disengages the rotary cutter from the guide. The retrograde drill pin is then retracted and simultaneously rotated for retrograde cutting of a socket or tunnel of desired depth in the tibia. A strand is passed through the cannulation of the drill pin into the joint. The end of the strand is retrieved from the anteromedial portal and a loop formed for subsequent graft installation. A similar technique is used to form a socket or tunnel in the femur except that a femur guide is used in place of the tibial guide. A graft of appropriate length is pulled through the anteromedial portal by the loops formed in the strands and the ends of the graft are drawn into the femoral and tibial sockets. The reconstruction is completed by securing the graft ends.

This application claims the benefit of U.S. Provisional Application No.60/735,197, filed Nov. 10, 2005 and U.S. Provisional Application No.60/794,512, filed Apr. 25, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of surgery and, moreparticularly, to methods of reconstructive knee surgery.

2. Description of the Related Art

Methods of anterior cruciate ligament (ACL) reconstruction usinginterference screw fixation are described, for example, in U.S. Pat.Nos. 5,211,647 and 5,320,626. In general, these methods of ACLreconstruction involve drilling a tunnel through the tibia, drilling aclosed tunnel (socket) into the femur, inserting a substitute ACL graftinto the tunnels, and securing the grafts to the walls of the tibial andfemoral tunnels using interference screws or the like. Accuratepositioning of the tibial and femoral tunnels is accomplished using adrill guide, examples of which are disclosed in U.S. Pat. Nos. 5,269,786and 5,350,383, incorporated herein by reference.

One drawback of the described methods of ACL reconstruction is thatforming the tibial tunnel involves removal of significant amounts ofbone material. U.S. Pat. No. 5,603,716 discloses a technique for ACLreconstruction that avoids the above-noted problem by forming sockets inboth the femur and the tibia using a coring bone harvester. Theharvester is impacted into bone to a desired depth so that bone materialcollects as a bone core within the harvester tube. The bone core isextracted from the bone socket using a simultaneous twisting and pullingmotion. Such harvesting of bone cores in the joint is technicallydifficult. Accordingly, the need exists for a method of ACLreconstruction, and related instrumentation, that provides tibial socketformation without the need for extracting a bone core to form a bonesocket and to avoid drilling through growth plates in skeletallyimmature patients. There is also a need for a minimally invasive methodof ACL reconstruction, and related instrumentation, that providesdrilling of femoral and tibial sockets or tunnels independently of oneanother and minimizes incisions of distal cortices and reducesintraarticular bone fragmentation of tunnel rims.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages of the prior art andfulfills the needs noted above by providing techniques and apparatus forcreating bone sockets and/or tunnels by drilling in a retrograde manner.The present invention advantageously utilizes a preloaded retrograderotary cutter that provides exact visual replication of tunnel or socketdiameter prior to drilling both the tibial and femoral sockets and/ortunnels.

More specifically, the present invention provides a method for ACLreconstruction which includes the steps of introducing a guide having arotary cutter engaged on a distal end thereof into a joint through aportal, introducing a pin having a distal end into the joint, insertingthe distal end of the pin into a corresponding cannulation in the rotarycutter, engaging the rotary cutter with the distal end of the pin andsimultaneously disengaging the rotary cutter from the guide by rotatingthe pin, and drilling into the bone to create the socket by rotating therotary cutter and moving the rotary cutter in a retrograde manner usingthe pin.

The present invention also includes a system for carrying out the abovemethod, including a rotary cutter comprising a cylindrically shaped bodyprovided with a threaded cannulation and radially outward cutting teethfor retrograde drilling of a socket in bone, a guide comprising athreaded post for engaging and mounting the rotary cutter, and a drillpin having a distal end corresponding to the cannulation of the rotarycutter, for engaging the rotary cutter. The system is designed so thatthe rotary cutter is transferred from the guide to the drill pin byadvancing the drill pin into the cannulation of the rotary cutter androtating the drill pin in a first direction to engage the drill pin withthe rotary cutter mounted on the guide, and simultaneously disengage therotary cutter from the guide.

The method and system for ACL reconstruction of the present inventionmay be employed in posterior cruciate ligament (PCL) reconstruction aswell.

Other features and advantages of the present invention will becomeapparent from the following description of the invention which refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate a retrograde rotary cutter according to thepresent invention;

FIGS. 2A and 2B illustrate a retrograde pin according to the presentinvention;

FIGS. 3A and 3B illustrate a C-ring and a retrograde rotary cutteraccording to the present invention;

FIG. 4 schematically illustrates an initial stage in the formation of atibial socket according to the present invention;

FIG. 5 schematically illustrates the formation of a tibial socket at astage subsequent to that shown in FIG. 4;

FIG. 6 schematically illustrates the formation of a tibial socket at astage subsequent to that shown in FIG. 5;

FIG. 7 schematically illustrates the formation of a tibial socket at astage subsequent to that shown in FIG. 6;

FIGS. 8A and 8B illustrate a drill depth grommet on a retrograde drillpin according to the present invention;

FIGS. 9A and 9B schematically illustrates the formation of a tibialsocket at a stage subsequent to that shown in FIG. 7;

FIG. 10 schematically illustrates the formation of a tibial tunnel at astage subsequent to that shown in FIG. 9A;

FIG. 11 schematically illustrates the formation of a tibial socket at astage subsequent to that shown in FIG. 10 or FIG. 9B;

FIG. 12 schematically illustrates the formation of a tibial socket at astage subsequent to that shown in FIG. 11;

FIG. 13 schematically illustrates an initial stage in the formation of afemoral socket according to the present invention;

FIG. 14 schematically illustrates the formation of a femoral socket at astage subsequent to that shown in FIG. 13;

FIG. 15 schematically illustrates the formation of a femoral socket at astage subsequent to that shown in FIG. 14;

FIG. 16 schematically illustrates the formation of a femoral socket at astage subsequent to that shown in FIG. 15;

FIG. 17 schematically illustrates the formation of a femoral socket at astage subsequent to that shown in FIG. 16;

FIG. 18 schematically illustrates the formation of a femoral socket at astage subsequent to that shown in FIG. 17;

FIG. 19 illustrates a schematic view of a knee joint undergoing graftinsertion according to an embodiment of the present invention; and

FIG. 20 illustrates a schematic view of a knee joint having undergonegraft insertion and fixation according to an embodiment of the presentinvention.

DETAILED DESCIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a technique for forming femoral andtibial bone sockets in a retrograde manner during ligamentreconstruction, for example, anterior cruciate ligament (ACL)reconstruction. The present invention also provides a method of graftinsertion and fixation employed in connection with the femoral andtibial sockets formed in accordance with the present invention.

Referring now to the drawings, where like elements are designated bylike reference numerals, FIGS. 1-2 illustrate a retrograde rotary cutter10 (FIGS. 1A-1C) which is adapted to be threadingly engaged with acannulated retrograde drill pin 50 (FIGS. 2A-2C).

Referring to FIGS. 1A-1C, the retrograde rotary cutter 10 features acylindrical body 11 having a plurality of cutting teeth 12 radiatingsymmetrically. A cannulation 13 through body 11 is provided withinternal screw threads 14. Cutting teeth 12 have edges extendingradially from cannulation 13 on a proximal cutting face 15, seen in planview in FIG. 1A. The edges of cutting teeth 12 continue axially alongthe side of the retrograde rotary cutter 10, which is orientedorthogonally to proximal cutting face 15. The edges end at a smooth,rounded distal end 16 of retrograde rotary cutter 10. Retrograde rotarycutter 10 is provided in a selected diameter corresponding to graft sizeof diameter substantially equal to the diameter of a replacement graftsubstitute for an anterior cruciate ligament (ACL).

Referring to FIGS. 2A-2B, retrograde drill pin 50 features a flutedregion 51 formed on distal end 52 of cannulated body 53, as shown indetail in FIG. 2B. Cannulated body 53 has a proximal end 54. Thecannulated body 53 is provided with screw threads 55 at distal end 52.The screw threads 55 are fashioned to engage corresponding threads 14 ofretrograde rotary cutter 10. Accordingly, the outer diameter of threadedregion 55 closely approximates the diameter of cannula 13 of theretrograde rotary cutter 10, to allow secure engagement of the outerthreaded region 55 with the inner threads 14 of retrograde rotary cutter10.

Retrograde drill pin 50 features visible calibrated depth markings 56lased onto the cannulated body 53. Between threads 55 and depth markings56, a shoulder 57 is formed to provide a stop where threads 55 end. Thelumen of cannulated body 53 accepts a trocar 58 having a pointed tip 59.When the trocar is removed, a strand can be passed through the lumen ofthe cannulated body 53, as described below in greater detail. Theproximal end 54 of cannulated body 53 is configured for chucking into arotary driver (not shown). The distal end 52 of cannulated body 53 isopen at the tip to expose the pointed end 59 when the trocar 58 isinserted into the cannulated body 53, as when drilling the assembledretrograde drill pin 50 into bone. Retrograde drill pin 50 includes asetscrew collar 62 for securing the trocar 58 in the cannulated body 53.

Referring to FIGS. 3A-3B, C-ring 70 features visible calibrated angularmarkings 70″ circumferentially lased onto the body (not shown). A groove(not shown) near one end of the C-ring 70 is provided to secure aretrograde drill guide sleeve 71. A holding member 72″ movable along thecircumference of C-ring 70 is provided to secure a tibial guide 72 or afemoral guide 83. The holding member 72″ facilitates angular adjustmentof the tibial guide 72 or the femoral guide 83 relative to theretrograde drill guide sleeve 71. The tibial guide 72 or the femoralguide 83 is provided with an insertion post 74 to allow secureengagement of the retrograde rotary cutter 10. A fixed angle drill guidemay be used instead of the drill guide C-ring 70.

A method of using the C-ring 70, the retrograde drill pin 50, the tibialguide 72, and the retrograde rotary cutter 10 to create a tibial socket81 of the present invention is described below with reference to FIGS.4-12, which illustrate a schematic anterior view of a knee in which ACLreconstruction is performed according to the present invention. In thefollowing embodiment of the present invention, a tibial socket 81 (showncompleted in FIGS. 10-12) is formed in a tibia 75.

Referring to FIGS. 4-5, the appropriate diameter retrograde rotarycutter 10 is threaded onto the insertion post 74 of the tibial guide 72.The tibial guide 72 is inserted through the anteromedial portal (notshown) and the retrograde rotary cutter 10 is placed on the anatomicalorigin of the ACL tibial insertion. The retrograde drill pin 50 isadjusted to an appropriate angle, to avoid existing tunnels and fixationhardware, for insertion onto the tibia 75.

Once the anatomical position in the joint for the tibial socket has beenidentified, and the appropriate drilling angle has been selected onC-ring 70, the retrograde drill guide sleeve 71 is inserted into thetibia 75 through a small stab incision on the tibia 75. The retrogradedrill pin 50 is drilled through the tibia, in a forward direction, tocreate pin hole 78 of a given diameter, for example 3mm, as shown inFIG. 5.

The retrograde drill pin 50 is drilled through the tibia 75 untilcontact is made with the retrograde rotary cutter 10 under arthroscopiccontrol, as shown in FIG. 6. Referring to FIG. 7, as threads of theretrograde drill pin 50 engage the retrograde rotary cutter 10, thereverse threads on the insertion post 74 of the tibial guide 72facilitate simultaneous disengagement of the retrograde rotary cutter 10from the insertion post 74 onto the retrograde drill pin 50. Oncesecurely engaged within the retrograde rotary cutter 10, the retrogradedrill pin 50 is rotated with a power driver (not shown) and retracted(retrograde) to cut through the tibial joint surface. In anotherembodiment, the attachment of the retrograde rotary cutter 10 to theretrograde drill pin 50 may be accomplished using a snap-fit.

As is illustrated in FIGS. 8A-8B, the drill depth grommet 80 on theretrograde drill pin 50 is advanced to the end of the retrograde drillguide sleeve 71 for socket depth assessment during drilling. As shown inFIG. 9A, the retrograde drill pin 50 is retracted to facilitateretrograde drilling of the tibial joint surface and into the tibia 75 tocreate a tibial socket 81. A desired depth D₁, preferably 25 mm., isobtained by reading the markings 80″ on the retrograde drill pin 50,recorded relative to the skin tibial surface prior to and during socketformation. Alternatively, a tibial tunnel 81″ may be created bycontinuing drilling through the distal cortex, as shown in FIG. 9B.

Once the desired socket depth D₁ is achieved, the retrograde drill pin50 is advanced forward until the retrograde rotary cutter 10 engages theinsertion post 74 on the tibial guide 72, as shown in FIG. 10.Reverse-drilling of the retrograde drill pin 50 securely engages theretrograde rotary cutter 10 on the insertion post 74 and simultaneouslydisengages the retrograde rotary cutter 10 from the threaded retrogradedrill pin 50. The retrograde drill guide sleeve 71 is pulled back, theretrograde drill pin 50 is removed from C-ring 70, and the tibial guide72 is removed from the knee joint. The retrograde drill pin 50 is leftin place in the pin hole 78 and the tibial socket.

Referring to FIG. 12, a tibial strand 82, such as Arthrex #2 FiberStick,described in U.S. Patent Application Publ. No. 2003/0153948,incorporated herein by reference, is passed through the cannulation ofthe retrograde drill pin 50 into the joint, and the retrograde drill pin50 is withdrawn. The end of the tibial strand is retrieved from ananteromedial portal (not shown) and a loop is formed for subsequent usein the installation of a graft.

Creation of a femoral socket 84 continues in a manner similar to thatfor creating the tibial socket 81 and is described below with referenceto FIGS. 13-18, which illustrate a schematic anterior view of a knee inwhich ACL reconstruction is performed according to the presentinvention. In the following embodiment of the present invention, afemoral socket 84 (shown completed in FIGS. 16-18) is formed in thefemur 76.

Referring to FIGS. 13 and 14, the appropriate diameter retrograde rotarycutter 10 is threaded onto the insertion post 74 of the femoral guide83. The femoral guide 83 is inserted through the anteromedial portal(not shown) and the retrograde rotary cutter 10 is placed on theanatomical origin of the ACL femoral origin. The retrograde drill pin 50is adjusted to an appropriate angle, to avoid existing tunnels andfixation hardware, for insertion onto the femur 76. In pediatric cases,it is preferable to use a 90 degree guide to position the femoral socketinferior to the physis to avoid the growth plate.

Once the anatomical position in the joint for the femoral socket hasbeen identified, and the appropriate drilling angle has been selected onC-ring 70, the retrograde drill guide sleeve 71 is inserted into thefemur 76 through a small stab incision on the lateral thigh (not shown).The retrograde drill pin 50 is drilled through the femur 76, in aforward direction, to create pin hole 78″ of a given diameter, forexample 3 mm, as shown in FIG. 15.

The retrograde drill pin 50 is drilled through the femur 76 untilcontact is made with the retrograde rotary cutter 10 under arthroscopiccontrol. Referring to FIG. 15, as threads of the retrograde drill pin 50engage the retrograde rotary cutter 10, the reverse threads on theinsertion post 74 of the femoral guide 83 facilitate simultaneousdisengagement of the retrograde rotary cutter 10 from the insertion post74 onto the retrograde drill pin 50. Once securely engaged within theretrograde rotary cutter 10, the retrograde drill pin 50 is rotated witha power driver (not shown) and retracted (retrograde) to cut through thefemoral joint surface and into the femur 76 to create a femoral socket84., as shown in FIGS. 15-16. A desired depth D₂, preferably 25 mm., isobtained by reading the markings 80″ on the retrograde drill pin 50,recorded relative to the skin femoral surface prior to and during socketformation.

Once the desired socket depth D2 is achieved, the retrograde drill pin50 is advanced forward until the retrograde rotary cutter 10 engages theinsertion post 74 on the femoral guide 83, as shown in FIG. 17.Reverse-drilling of the retrograde drill pin 50 securely engages theretrograde rotary cutter 10 on the insertion post 74 and simultaneouslydisengages the retrograde rotary cutter 10 from the threaded retrogradedrill pin 50. The retrograde drill guide sleeve 71 is pulled back, theretrograde drill pin 50 is removed from C-ring 70, and the femoral guide83 is removed from the knee joint. The retrograde drill pin 50 is leftin place in the pin hole 78″ and the femoral socket 84.

Referring to FIG. 18, a femoral strand 85, such as Arthrex #2FiberStick, described in U.S. Patent Application Publ. No. 2003/0153948,is passed through the cannulation of the retrograde drill pin 50 intothe joint and the retrograde drill pin 50 is withdrawn. The end of thefemoral strand 85 is retrieved from an anteromedial portal (not shown)and a loop 91 is formed for subsequent use in the installation of agraft.

A soft tissue graft or a composite femoral bone/tendon allograft isprepared for insertion and fixation into the femoral socket 84 andtibial socket 81. The graft is selected so that its diameter correspondsto the diameters of the femoral and tibial sockets 84, 81.Alternatively, the correct diameter of the retrograde rotary cutter 10may be selected to correspond to the diameter of a previously-preparedgraft. The graft 86 is slightly shorter than the summed lengths of thefemoral and tibial sockets and the intraarticular length of a damagedligament origin and insertion points, to facilitate appropriate tensionin the graft 86 during fixation. For example, assuming that the lengthD₁ of the tibial socket 81 is about 25 millimeters, the length D₂ of thefemoral socket 84 is about 25 millimeters, and the intraarticular lengthD between the two sockets is about 30 millimeters, the total length L ofthe graft 86 is slightly less than about (25+25+30) millimeters.

Installation of the graft 86 is illustrated schematically in FIGS.19-20. The graft 86 is pulled through the anteromedial portal (notshown) by the loops 90, 91 formed in the tibial strand 82 and thefemoral strand 85. The ends of the graft 86 are drawn into the femoral84 and tibial 81 sockets, as shown in FIGS. 19-20. The graft suture 93is tied over the lateral femoral cortex. The knee is brought into nearextension, the graft 86 appropriately tensioned and the graft suture 92is tied over the tibial cortex. A graft tension measuring device, suchas Arthrex Tensioning Device AR-4002, may be used to quantify thetension in the graft 86 during tibial fixation. The sutures 92, 93 maybe tied over a button 87, such as the Arthrex titanium Suture Button,Part No. AR-8920. The sutures 92, 93 may be secured in any conventionalmanner, such as using ligament washers and post designs, or interferencescrews placed in a retrograde fashion with a specially designedretrograde screw driver, or with a cross pin.

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the invention is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, embodiments andsubstitution of equivalents all fall within the scope of the invention.Accordingly, the invention is not to be considered as limited by theforegoing description, but instead is limited by the scope of theappended claims.

1. A method of forming a hole in a bone, comprising: introducing a guidehaving a rotary cutter engaged on a distal end thereof into a jointthrough a portal; introducing a pin having a distal end into the joint;inserting the distal end of the pin into a corresponding cannulation inthe rotary cutter; securing the rotary cutter to the distal end of thepin and simultaneously disengaging the rotary cutter from the guide byrotating the pin; and drilling into the bone to create the hole byrotating the rotary cutter and simultaneously moving the rotary cutterin a retrograde manner into the bone using the pin.
 2. A methodaccording to claim 1, wherein the rotary cutter is threadably engagedwith the pin.
 3. A method according to claim 1, further comprising thestep of measuring the depth of the socket using a grommet disposedaxially on the drill pin.
 4. A method according to claim 1, wherein thestep of introducing the drill pin includes the step of aligning the pinrelative to the guide using a C-ring.
 5. A method according to claim 4,wherein the guide is movable along the circumference of the C-ring toadjust the angle of the pin relative to the guide.
 6. A method of kneereconstruction, comprising: forming a hole in a femur in a retrogrademanner in accordance with the method of claim 1; forming a hole in atibia in a retrograde manner in accordance with the method of claim 1;introducing a graft into the joint between the femur and tibia; andsecuring the respective ends of the graft in the holes formed in thefemur and the tibia.
 7. A method according to claim 6, wherein the stepof introducing a graft into the joint between the femur and the tibiacomprises: introducing a tibial strand through a cannulation of a pinintroduced into the tibia for forming a tibial hole; retrieving from ananteromedial portal the free end of the tibial strand exiting the tibialhole; forming a loop in the tibial strand; introducing a femoral strandthrough a cannulation of a pin introduced into the femur for forming afemoral hole; retrieving from an anteromedial portal the free end of thefemoral strand exiting the femoral hole; forming a loop in the femoralstrand; securing respective ends of a graft in the loops of the femoraland tibial strands; and pulling the graft through the anteromedialportal and into the femoral and tibial holes using the femoral andtibial strands.
 8. A system for retrograde drilling of openings in bone,comprising: a rotary cutter comprising a cylindrically shaped bodyprovided with a cannulation and radially outward cutting teeth forretrograde drilling of a hole in bone; a guide including a post forengaging and mounting the rotary cutter; and a pin having a distal endcorresponding to the cannulation of the rotary cutter, for engaging therotary cutter, wherein the rotary cutter is transferred from the guideto the pin by advancing the pin into the cannulation of the rotarycutter and rotating the pin in a first direction to engage the pin withthe rotary cutter mounted on the guide, and simultaneously disengage therotary cutter from the guide.
 9. A system for retrograde drilling ofopenings in bone as recited in claim 8, further comprising a C-ring formounting the guide and positioning the guide with respect to the bone,the C-ring further including a sleeve for guiding the pin such that thepin is directed into engagement with the cannulation of the rotarycutter mounted on the guide, as the pin is advanced through the sleeve.10. A system for retrograde drilling of openings in bone as recited inclaim 9, wherein the position of the guide is adjustable on the C-ringto facilitate angular adjustment of the guide relative to the pin.
 11. Asystem for retrograde drilling of openings in bone as recited in claim10, wherein the C-ring is provided with calibrated angular scalemarkings.
 13. A system for retrograde drilling of openings in bone asrecited in claim 11, wherein the pin comprises a cannulated shaft havinga proximal end and a distal end, a fluted region formed on the distalend of the cannulated shaft for drilling through bone; and a threadedportion located near the distal end of the cannulated shaft andcorresponding to inner threads of the cannulation of a rotary cutter.14. A system for retrograde drilling of openings in bone as recited inclaim 13, wherein the pin is provided with a depth-measuring grommetlocated axially on the retrograde pin for depth assessment duringdrilling.